Your question needs a lot more info before any realistic help can be given.. Wheelbase, curb weight, frame width and length. Intended use. Main rail width/depth?

 

Curb weight is 1000kg, 103 Inch wheel base, standard model frame width and 6 inch longer length at rear. 6 Inch Z in front 12 Inch in rear.

 

engine-trans

Also engine and trans weight. a 1. 6 liter 4 , or a CAT diesel ?

 

Engine is small black ford with t5 transmission

 

I use 3/16 myself..how that translates to mm dunno right now..

Sam

 

A lot of things goes into play when building these things,, What type of tabs and motor mounts you will be building,,, There's ways to use 3/16 And different ways to use 1/4,,, So without knowing how you plan to do the mounts and tabs,, Hard to say,,, It has a lot to do with your welding skill's also..

Depending on how I make mine,, I usaully use 3/16...Or tubing,

There's all kind of ways to build Mounts and tabs..

Here's something that might give you some ideas on tabs and motor mounts..

http://www.hotrodders.com/forum/making-willys-frame-148235.html
http://www.hotrodders.com/forum/new-homemade-ratrod-making-138193.html
http://www.hotrodders.com/forum/building-homemade-c-cab-191990.html

 

Here's some pics of the 507" Cadillac installation after pulling the 327. I used some 1/8" plate and welded it to the boxing plates for a thickness of 1/4". The rest of the mount material is 1/4", could use 3/8 but that is probably overkill.

The tig welding was done outside during a breezy day so it's not perfect but it is very strong, drilled 4 holes in each plate to utilize some plug welding ....... I think most guys use 1/4" so don't get hung up on the thickness, just bevel the edges a bit and make everything is nice and clean for a good weld.